In some outdoor water well systems a hollow tank is connected into the line leading from the pump to the various water outlets in the water system. The tank fills up to a level that will maintain a relatively constant water pressure in the line. In this way the pump is not required to have a capacity as large as the maximum water usage rate (all outlets opened at the same time). During temporary periods of high water usage the tank can supply part of the needed water to the open outlets while maintaining a satisfactory pressure in the system.
Commonly, the pump motor is controlled by a pressure switch that responds to changes in line pressure, to turn the motor on or off, according as the line pressure falls below or exceeds a predetermined pressure setting. The line pressure maintains a fairly constant level in the tank, so that the tank is always assured of having enough water to meet any temporary high demand situation.
In conventional systems the pressure switch is arranged directly in the water line. During winter operations it is possible for ice to form in the switch or switch actuator, thereby causing a switch malfunction. Water leakage into the switch can also cause a malfunction. Some switch parts in direct contact with the water can corrode after extended service, thereby requiring switch replacement.